Lithium, Magnesium, and Zinc Centers N,N'-Chelated by an Amine-Amide Hybrid Ligand.

The synthesis and structure of lithium, magnesium, and zinc complexes ,'-chelated by a hybrid amine-amido ligand ([2-(MeNCH)CHNR], abbreviated as LR, where R = H, SiMe, or Bn) are reported. The reaction of the least sterically demanding LH with various magnesium sources gives the hexameric imide [LMg] () by the elimination of -butane from LHMgBu () or by the reaction of LHLi () with MeMgBr. [LH]Mg () is obtained through the addition of 0.5 equiv of BuMg or Mg[N(SiMe)] to LH and with 1 equiv of BuMg reacting to . Both LHMgN(SiMe) () and isostructural LHZnN(SiMe) () have been prepared using two different approaches: monodeprotonation of LH by Zn/Mg[N(SiMe)] in a 1:1 ratio or ligand substitution of or LHZnEt () by 0.5 equiv of Sn[N(SiMe)]. The reactions of or with provide the heterotrimetallic complex [LH]LiMg (). Benzyl- or trimethylsilyl-substituted anilines [L(SiMe)H () and L(Bn)H ()] with 0.5 equiv of BuMg allow the formation of homoleptic bis(amides) of the [L(R)]Mg type ( and ). Nevertheless, only the silylated secondary amine is able to provide the heteroleptic -butylmagnesium amide L(SiMe)MgBu () upon reaction with an equimolar amount of BuMg. Similarly, , [LH]Zn (), L(R)ZnEt ( and ), and [L(R)]Zn [R = SiMe () and Bn ()] were prepared by the monodeprotonation of LH or L(R)H using EtZn in the corresponding stoichiometric ratio. LHZnI was prepared by the nucleophilic substitution of an ethyl chain in by molecular iodine. A heterometallic complex, [LH]LiZn (), analogous to was prepared from or with 1 or 2 equiv of , respectively.